RAID levels (0, 1, 5, 6, 10)
RAID combines drives for speed, redundancy, or both. RAID 0 stripes with no protection, RAID 1 mirrors, RAID 5 uses single parity (survives one drive loss), RAID 6 uses double parity (survives two), and RAID 10 mirrors then stripes for speed plus redundancy.
RAID 0 stripes data across drives for maximum throughput and full capacity but loses everything if any one drive fails. RAID 1 mirrors two drives, so a copy survives a single failure at the cost of half the raw capacity. RAID 5 spreads parity across all members and tolerates one failed drive; RAID 6 keeps two parity blocks and tolerates two, which matters as drives grow and rebuilds take longer.
RAID 10 combines mirroring and striping, giving strong random write performance and fast rebuilds while surviving at least one drive loss per mirror pair. Parity RAID (5 and 6) carries a write penalty because each write recomputes parity, and rebuild time on large SATA drives can stretch into days, which is the window where a second failure kills a RAID 5 array.
For a purchased server, match RAID level to workload and drive size. Large-capacity arrays favor RAID 6 over RAID 5 for the second-failure margin. Databases and VM hosts favor RAID 10. Confirm the controller supports the level you want in hardware, and remember RAID is not a backup.
Need a build that gets this right? We spec, assemble and burn-in enterprise servers in China and ship them worldwide with a 1-year warranty. Tell us the workload and get a quote the same business day.